Uncle Sam .... Late to the Gate and the Party again.
"it might be difficult or impossible for the USA to know who had done it - or even if anything had actually been done."
What do you think are the Chances of Conficker Chappies being au fait with Space Superiority Programs for Projection of Invisible and Intangible Might which can Disrupt Nations Sublimely ...... to Foreign Order*?
And what of Blighty's CyberCom Service for InterNetional Provisional Command and Control of IntelAIgent Space Waves? Hush, hush or a non starter, with there being no bods and boffins at the Real SMART Control? That of course, leaves the nation as vulnerable as a virgin in a brothel to wanton abuse and would be a scandal, as well as a crying shame.
* And man, is that a Lucrative Invisible Export Earner for the Public Purse or is that a Lucrative Invisible Export Earner for the Private Sector.